• The Korean Journal of Ceramics
• /
• 제1권4호
• /
• pp.191-196
• /
• 1995

Using sol-gel processing method, thin films of lathanum modified lead titanate(PLT) on Corning 7059 glass were prepared. A differential thermal analysis (DTA/TG) curve of gel powder and infrared spectra (FT-IR) of the films were measured to estimate residual organices in them. The heat-treated films were characterized by X-ray diffraction(XRD). Microstructures of the films were observed by a scanning electron microscope (SEM). Optical properties of the films were determined by a UV-VIS spectrophotometer. The waveguiding properties and optical attenuation were measured with the end coupling method and the cut back method. Effects of the drying conditions on the transmittance and the propagation loss of the films were investigated. Experimemtal results showed that the content of residual organics in the film decreased as the drying temperature of the film increased. As the La content of the film increased, the grain size decreased and the transmittance increased. The transmittances of the films increased with the increasing of the drying temperature. The propagation losses in the film decreased as the drying temperature increased.

• Journal of the Korean Wood Science and Technology
• /
• 제45권6호
• /
• pp.762-771
• /
• 2017

Predicting the amount and distribution of moisture content within wood allows calculating the various mechanical dynamics of the wood as well as determining the drying time. For boxed-heart wood with a large cross-section, since it is difficult to measure the moisture content of the interior, it is necessary to predict the moisture content distribution. This study predicted the moisture movement in boxed-heart red pine timber, during high temperature drying, by using the three-dimensional finite difference method for the efficient drying process. During drying for 72 h, the predicted and actual moisture content of the tested wood tended to decrease at a similar rate. In contrast, the actual moisture content at 196 and 240 h was lower than predicted because surface checking of the wood occurred from 72 h and excessive water emission was unexpectedly occurred from the checked and splitted surface.

• 한국축산시설환경학회지
• /
• 제3권2호
• /
• pp.133-143
• /
• 1997

Optimal conditions for collecting, storing and drying temperature to utilize slaughter porcine blood for blood meals and the effects of blood meal on growth in broiler chicks were investigated. Dry matter and protein contents of slaughter procine blood were 19.5% and 77%(dry basis), respectively. As for the composites of amino acids in the blood, aspartic acid, arginine, glycine, histidine, leucine, lysine, phenylalanin threonine were shown high. There was no significant difference between the collections by bloodletting and vacuumming in terms of microbial contamination. Storage of slaughter porcine blood showed no differences in protein, DNA and triglyceride contents and pH between the storage methods of freezing (-20$^{\circ}C$) and refrigerating (-4$^{\circ}C$). In case of room temperature storage, however, the decrease in pH and the appearance of new protein due to microbial contaminations increased as the storage periods were prolonged. When drying was done by flash methods, the drying period got shortened as the temperature became higher, yet protein and triglyceride were destoryed more. When drying was done over 120$^{\circ}C$, even at the same degree, the breakdowns of protein and triglyceride increased more as drying period got longer. In feeding trials of broiler chicks, dietary supplementation of the flash dried blood meal at 2% level showed significant difference in growth rate(P＜.05%). These results indicated that the appropriate handling and manufacturing of slaughter porcine blood enabled the blood to be used as a protein source for broiler chicks.

• 농약과학회지
• /
• 제12권4호
• /
• pp.368-374
• /
• 2008

길항력이 있는 그람음성균들의 생물적 방제제로 성공적인 개발은 균의 건조와 저장시의 낮은 생존을 때문에 건조제형으로 만드는 것은 제한되어있다. 그람음성균의 배양시 높은 염(NaCl)의 첨가는 삼투압 조절제인 osmolyte의 생성을 유도하여 건조 시 생존율을 높인다고 알려져 있다. 그람음성의 길항력을 내는 비병원성 Erwinia carotovora subsp. carotovora(Ecc) 9-3의 건조와 저장시의 염의 영향에 관해 연구하였다. Ecc 9-3의 생장률은 0.5 M의 염이 첨가되어 있는 배지에서 큰 차이가 없었지만 0.7 M의 염이 첨가된 배지에서는 급격하게 낮아진 것을 확인하였다. 건조와 저장시의 생존율은 0.5 M의 염을 넣은 배지가 염을 넣지 않은 배지보다 상온건조와 동결건조에서 각각 2배 그리고 3배의 높은 생존율을 얻었다. 건조 후 저장에서도 역시 염이 높을수록 Ecc 9-3의 생존율이 더 높았다. 그리고 상온건조와 동결건조 모두 $4^{\circ}C$에 저장하였을 때 생존율에 큰 차이가 없었다. 그러나 생존율은 $27^{\circ}C$, $37^{\circ}C$에 저장하였을 때 염의 농도가 높을수록 생존율이 증가하였다. 첨가제 실험에서는 lactose가 동결건조와 상온건조 모두에 영향을 주었고 dextrin은 상온건조에 큰 영향을 주었다.

• 한국식품과학회지
• /
• 제28권6호
• /
• pp.1126-1134
• /
• 1996

삼투처리로 전처리한 당근의 건조특성을 알기 위해 건조와 재수화 공정을 행하여 물리적인 특성을 조사하고, 수분이동 메카니즘을 규명하기 위해 확산 방정식과 건조 모델을 적용하여 알아보고자 하였다. 열풍 건조시 건조특성은 고온과 낮은 상대습도의 조건에서 건조효율이 우수하였으며, 갈변도나 specific volume 등도 높은 값을 보였으며 전반적 색차 또한 큰 값을 보였여 갈변정도와 유사한 경향을 보였다. 재수화 특성도 고온과 낮은 상대습도에서 건조한 것이 대체적으로 복원률과 재수화성이 높게 나타나 건조 특성이 재수화시에도 유사한 경향으로 나타남을 알 수 있었다. 수분의 이동을 나타내는 확산계수는 고온과 낮은 상대습도에서 높은 확산계수를 가졌으며, 온도의 영향이 상대습도보다 크게 나타나 상대습도를 낮추는 것 보다 건조온도를 높이는 것이 더 효과적인 운용방법임을 알 수 있었다. 건조과정을 기존의 건조모델로 표현하고자 적합성 여부를 조사해 본 결과 건조조건에 관계없이 quadratic model이 가장 높은 적합도를 보여 이 모델로서 건조시 수분함량의 감소를 시간의 함수로 나타낼 수 있었다. 건조시간과 풍속을 변화시키면서 실험을 행한 결과 시간에 따른 carotene 함량과 수분함량은 polynomial 형태로 모델화 할 수 있었고 풍속이 강할수록 평형수분함량 도달 시간은 빨라졌으나 1.2 m/s 이상의 풍속에서는 그 차이가 크지 않았으며, carotene 함량도 유사한 경향이었다. 재수화 특성값도 빠른 풍속에서 건조한 당근일수록 우수한 것으로 나타났으며, carotene 함량이나 전반적인 색차도 건조 후의 특성이 그대로 유지되었다. 기존모델과의 적합도를 살펴보면 풍속에 관계없이 quadratic mode이 가장 높은 적합도를 보여 건조시 수분의 이동을 예측할 수 있을 것으로 생각된다.

• Journal of the Korean Wood Science and Technology
• /
• 제39권2호
• /
• pp.117-124
• /
• 2011

The possibility of using the properties of an ultrasonic wave as a means for monitoring the moisture content of a board during drying was investigated. The ultrasonic wave signals are influenced by moisture content and other factors such as temperature, moisture gradient and coupling area. The effect of temperature was examined by measuring the transit times, amplitudes and velocities of ultrasonic waves transmitted through air, a metal bar and a board at various temperatures. The effect of a moisture gradient was studied using a model specimen composing five wood pieces of various moisture contents. The velocity and amplitude of the ultrasonic waves transmitted through air increase with temperature, while those through a metal bar and a board decrease. It was confirmed that the temperature effect is partially attributed to the change of transducer's properties. The effect of a moisture gradient on the velocity of an ultrasonic wave varies with the average moisture content of a board. As the dimension of the end face of a board increases the velocity of an ultrasonic wave increases and low frequency components more dominates than high frequency components. The transit times of ultrasonic waves transmitted through a board during kiln drying reflect the temperature steps in the drying schedule and the transducer temperatures.

• 한국의류산업학회지
• /
• 제13권4호
• /
• pp.635-643
• /
• 2011

This study was investigated to evaluate the physiological responses on T-shirts manufactured with selected functional materials by body parts which were selectioned on the distribution of sweating and temperature change. Seven healthy men in twenties were participated in a climate chamber of $27{\pm}0.5^{\circ}C$ and $50{\pm}1%RHC$. Three kinds of T-shirts named 'D1', 'D2' and 'Poly' were used as experimental clothings. Four kinds of functional materials of quick absorbing/drying were used in all section in 'D1', but two kinds of functional materials used partially in 'D2'. 'Poly' T-shirts used only polyester. In an experimental schedule of 90 minutes, which were consisted of 'Rest', twice of 'Exercise' and twice of 'Recovery' periods, the subjects walked on a treadmill with 60% of $VO_2max$. As a physiological responses, the microclimate temperature, surface temperature(skin, clothing) and sweat rate were measured. Temperature regulation was kept well in 'D1' rather than other T-shirts. The quick absorbing/drying T-shirts showed its performance well as the exercise goes on the second half. With these results in mind, 'D1' will be more effective for long hours exercise such as climbing rather than short hours exercise.

• 대한환경공학회지
• /
• 제30권7호
• /
• pp.694-699
• /
• 2008

유기성 슬러지의 직접 매립 금지와 가까운 장래에 해양투기가 금지될 전망이므로 발생되는 슬러지의 적절한 처리에 대한 발전된 기술의 연구가 필요하다. 본 연구에서는 슬러지 건조기술 중 하나인 폐유를 활용하여 하수슬러지를 유중 건조시키는 방법에 대한 연구를 수행하였다. 이 공정의 기본 원리는 오일을 가열함으로써 형성되는 급격한 압력변화에 의해 슬러지 공극을 통하여 수분이 빠르게 증발하도록 하는 것이다. 일련의 건조 실험 결과, 건조온도, 건조시간, 오일종류, 슬러지 형상 등 중요한 실험변수에 따른 건조곡선이 얻어졌다. 건조 오일로 폐식용유를 사용한 경우 건조시간에 따른 수분함유량 변화는 건조시간 10분이 지나면서 현저히 감소하기 시작하여 14분 이후에는 건조온도에 관계없이 수분함유량이 5% 이내로 감소하였다. 유중 건조 온도는 120$^{\circ}C$에 비해 140$^{\circ}C$ 이상에서 수분 증발이 급격히 증가한 것으로 나타났다. 그러나 140$^{\circ}C$ 이상에서는 큰 차이를 나타내지 않았다. 슬러지 직경이 감소할수록 효율적으로 건조되는 것으로 나타났는데 이는 단위체적당 표면적의 증가에 기인하는 것이다. 오일 종류의 변화에 따른 영향을 살펴보면 폐 엔진오일을 사용한 경우 점도가 증가함에 따라 폐식용유에 비하여 수분 증발이 현저히 지체되는 현상이 나타났다. 그러나 건조온도 140$^{\circ}C$ 이상에서는 120$^{\circ}C$에 비하여 건조시간이 경과함에 따라 수분 증발이 비교적 크게 증가하는 결과를 나타내었다. 그러므로 폐오일의 종류에 관계없이 건조온도는 140$^{\circ}C$ 이상으로 유지하는 것이 바람직한 것으로 사료된다.

• 한국염색가공학회지
• /
• 제21권4호
• /
• pp.23-32
• /
• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air($50^{\circ}C$) and room temperanrre($25^{\circ}C$) drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.

• Journal of Biosystems Engineering
• /
• 제3권2호
• /
• pp.114-125
• /
• 1978

The use of petroleum fuels in grain drying causes problems of high cost and management. To solve these problems, it is required to study on soLar energy as an alternative to petroleum fuels for grain drying. The purposes of this study were to find out the optimum received area and air flow rate of a flat-plate solar air collector for grain drying and to assess its effects on grain drying with a small grain bin. The results of this study are summarized as follows ; 1. The calculated optimum tilt angles of the collector in the summer and autumn drying seasons were 20 and 50 degress, respectively, in suwon area. 2. The outlet temperature of the collector was $36^\circ C$ on the daily average with the maximum of $36^\circ C$ at 12:00 o clock. Solar radiation on the collector surface was 1.04 ly( 1 langley = 1 cal/$cm^2$) per minute on the daily average and 1.30 ly per minute on the maximum at 11:00am. The thermal efficiency of the collector was 62.4 percent on the daily average, and the air flow-rate per unit receiving are was 1.03 $m^3$/min/$m^2$.4. The calculated optimum receiving area and the air flow-rate per unit cubic volume for paddy in autumn drying season was 2 $m^2$ and 2$m^3$/min , respectively. 5. not significantly difference in the collector efficiency was appeared between the rotating and fixed type of solar collector. 6. For drying of wheat with 0.6 meter of the depth in the bin, approximately 9 hours were required to reduce the moisture content from 21.6% to 13% with air follow rate of 5 $m^3$/min an initial moisture per cubic meter of wheat and with air temperature of $52^\circ C$. 7. In the drying test of rough rice with a turning operation in a grain bin approximately 21 hours were required to reduced the moisture from 21% to 14.5% with airflow rate of 2 $m^3$/min per cubic meter of rice and the air temperature of $43.5^\circ C$. 8. Over-drying at the bottom and less -drying at the top of the grain mass was resulted from the high -temperature of drying air which was obtained from the flat-plate solar collector in this test. An appropriate operation should be prepared for the uniform moisture of the grain in the bin.